CSCE101 – Ch 3 September 14 & 16, 2006

Chapter 3 Computer Software = System Software + Application Software Delineation unclear – (ex. Microsoft Antitrust) System Software = Operating System + Device Drivers + Utility Programs Operating System Interface:

Operating Systems UNICOS,COS MVS,VM Windows, Unix Mac OS PenRight

Application Software Internet Explorer, Mozilla Firefox MS Word Notepad Dropbox Application software is often platform- dependent

Functions of OS Provides User Interface Manages Itself Manages CPU Manages Memory Manages Files Manages Security

Managing Itself ROM BIOS, Bootstrapping, Cold Boot, Warm Boot Diagnostics, POST, Boot Device, Boot Sector, Embedded Systems, Ctrl-Alt-Del Supervisor (Kernel) – critical piece of software. Considered a challenging programming task. Microkernels vs. monolithic kernels System calls

Boot Process When you turn your computer on… …the processor automatically begins… …executing the part of the operating system’s startup system (BIOS) located in ROM. These instructions help load the operating system from the hard disk into RAM (main memory), and… …then they pass control to the OS.

Manages CPU CPU – Central Processing Unit Von Neumann’s Architecture – one process per CPU Sequential vs. Parallel processing Single processor, dual core, multiple processors Multitasking Multiprocessing, thrashing Time-sharing, priority (dynamic and static) Multiprogramming

Manages Memory Memory, storage – Primary, secondary RAM Storage Hierarchy - caches, buffers, registers Bottlenecks Spooling Virtual memory and paging

File Management Folders (directories) Paths C:/mydocuments/termpaper/section1.doc File extensions

Manages Security Access control Passwords Firewalls Interprocess protection